Intro to Cranial Nerves Flashcards
CN I
Olfactory Nerve
CN II
Optic Nerve
CN III
Oculomotor Nerve
CN IV
Trochlear Nerve
CN V
Trigeminal Nerve
CN VI
Abducens Nerve
CN VII
Facial Nerve
CN VIII
Vestibulocochlear Nerve
CN IX
Glossopharyngeal Nerve
CN X
Vagus Nerve
CN XI
Accessory Nerve
CN XII
Hypoglossal Nerve
Cranial Nerve Motor Nuclei
Origin for somatic motor fibers
Equivalent of ventral horn of spinal cord
Cranial nerve motor nuclei
Cranial nerve sensory ganglia
located outside the brainstem, have peripheral and central processes that terminate in a cranial nerve sensory nucleus
Equivalent of spinal ganglia
Cranial nerve sensory ganglia
Cranial nerves that contain parasympathetic fibers
CN III, CN VII, CN IX, CN X (oculomotor, facial, glossopharyngeal, and vagus respectively)
Parasympathetic nuclei
origin for preganglionic parasympathetic fibers of the head
Equivalent to lateral horn of gray matter of the spinal cord at S2-S4
Parasympathetic nuclei
Parasympathetic ganglion
COPS (ciliary, otic pterygopalatine, submandibular)
How to postganglionic parasympathetic fibers reach their end targets?
They hitch hike along branches of CN V-Trigeminal nerve
Superior cervical ganglion
Sympathetic fibers ascend in the sympathetic chain and synapse here because it is the superior termination of the sympathetic chain.
Ways that postganglionic sympathetic fibers can reach their targets
1.) Hitchhiking with internal carotid artery, then onto the external carotid artery, 2.) following branches of internal carotid artery then hitching a ride with the trigeminal system, 3.) travel on their own before joining with other nerves.
Purely sensory cranial nerves
CN I-Olfactory, CN II-Optic, CN VIII Vestibulocochlear
What passageway does CN I pass through to enter the skull?
The cribriform plate of the ethmoid bone. These axons terminate in the olfactory bulb and processes from the olfactory bulb pass through the olfactory tract into the brain
Which system is the only sensory system that does not pass through the thalamus before reaching the cortex?
The olfactory tract
Anosmia
Loss of sense of smell
What forms the optic nerve?
Ganglion cells of the retina
how does the optic nerve enter the cranial cavity?
The optic canal
What forms the optic chiasm
The uniting of the optic nerves from either side of the face.
How does the vestibulocochlear nerve exit the skull?
Via the internal acoustic meatus
What is the vestibular nerve responsible for?
Hearing
What is the cochlear nerve responsible for?
Balance
Where are vestibular cell bodies located?
The vestibular ganglion
Where do vestibular cell bodies send their central processes to?
The vestibular nuclei
Where do vestibular cell bodies send their peripheral processes to?
The vestibular apparatus composed of the utricle, saccule, and semicircular canals
Where are cochlear cell bodies located?
The cochlear (spiral) ganglion
Where do cochlear cell bodies send their central processes to?
The cochlear nuclei
Where do cochlear cell bodies send their peripheral processes to?
The cochlea
What are the purely motor cranial nerves?
CN III-Oculomotor, CN IV-Trochlear, CN VI-Abducens, CN XI-Spinal Accessory, CN XII-Hypoglossal
What fibers are found in the oculomotor nerve?
Somatic motor and parasympathetic fibers
Through what cranial opening does the oculomotor nerve exit the skull?
Superior orbital fissure
What are the targets of the somatic motor component of the oculomotor nerve?
Levitator palpebral superiors, and all extraocular muscles except the lateral rectus and superior oblique
Where are the cell bodies of the somatic motor component of the oculomotor nerve located?
Oculomotor nucleus of the midbrain.
What does the superior division of III supply?
The superior rectus and elevator palpebrae muscles
What does the inferior division of III supply?
The medial rectus, inferior rectus, and inferior oblique muscles
What are the targets of the parasympathetic fibers of the oculomotor nerve?
smooth muscular sphincter pupillae and ciliaris muscle
Where are the preganglionic parasympathetic cell bodies of the oculomotor nerve found?
Edinger-Westphal Nucleus
Where do fibers of the preganglionic parasympathetic fibers of the oculomotor nerve travel and synapse?
In the inferior division of III and synapse in ciliary ganglion.
How do postganglionic parasympathetic fibers of the oculomotor nerve get to the eye?
Via the short ciliary nerve
Lesion of oculomotor nerve
Droopy upper eyelid, dilated pupil, pupil directed down and out.
What fiber types are found in the trochlear nerve?
Somatic motor
How does the trochlear nerve exit the brainstem?
DORSALLY
How does the trochlear nerve enter the orbit?
Via the superior orbital fissure
Where are the cell bodies of the trochlear nerve found?
In the trochlear nucleus of the pons
Lesion of the trochlear nerve
Patient is unable to look down when the eye is ADducted
What fiber types are found in the abducens nerve?
Somatic motor
Where do the cell bodies for the abducens nerve originate?
In the abducens nucleus
What are the targets of the abducens nerve
lateral rectus muscle
What are the targets of the trochlear nerve?
Superior oblique muscle
Where does the abducens nerve run through?
The cavernous sinus with the internal carotid artery
How does the abducens nerve enter the orbit?
Via the superior orbital fissure
Lesion of the abducens nerve?
The patient is unable to abduct the eye
What types of fibers are in the spinal accessory nerve?
Somatic motor only
What are the targets of the spinal accessory nerve?
Trapezius and Sternocleidomastoid muscle
Where are the cell bodies of the spinal accessory nerve found?
Spinal accessory nucleus of the upper 5 segments of the spinal cord
What openings does the spinal accessory nerve pass through?
Enters skull via foramen magnum, exits skull via jugular foramen
Lesion of spinal accessory nerve
Patient shows shoulder droop
Types of fibers found in the hypoglossal nerve
Somatic motor
What are the targets of the hypoglossal nerve
All intrinsic and extrinsic muscles of the tongue except paltoglossus
Where are the cell bodies of the hypoglossal nerve found?
Hypoglossal nucleus
How do hypoglossal nerves exit the cranial cavity?
Via the hypoglossal canal
Lesion of hypoglossal nerve
protruded tongue deviates to the affected side.
Mixed Cranial Nerves
Trigeminal-CN V, Facial-CN VII, Glossopharyngeal-CN IX, Vagus-CN X
What types of fibers does the trigeminal nerve contain?
Somatic motor and somatic sensory fibers
Where are the cell bodies of origin for the somatic motor fibers of the trigeminal nerve?
Trigeminal motor nucleus in the brainstem
Where are the cell bodies of origin for the somatic sensory fibers of the trigeminal nerve?
Trigeminal ganglion located on the petrous ridge of the temporal bone
Branches of the trigeminal nerve and their exits points
V1-Opthalmic, superior orbital fissure
V2-Maxillary, foramen rotundum
V3-Mandibular, foramen ovale
Which division of the trigeminal nerve contains motor fibers?
The mandibular division
How does the facial nerve leave the cranial cavity?
The internal acoustic meatus
What fibers are found in the facial nerve?
Somatic motor, preganglionic parasympathetic, somatic sensory, and taste fibers
Where do somatic motor fibers of the facial nerve have their cell bodies located?
The facial motor nucleus
Targets of the somatic motor fibers of the facial nerve?
Muscles of facial expression, stapedius, stylohyoid, and posterior belly of the digastric muscle.
Where are the cell bodies of the preganglionic parasympathetic fibers of the facial nerve located?
Superior salivary nucleus
What are the two branches of the preganglionic parasympathetic fibers of the facial nerve? and where do they synapse?
Greater petrosal nerve–>Pterygopalatine ganglion
Chora Typampani–>submandibular ganglion
Targets of greater petrosal nerve/pterygopalatine ganglion?
lacrimal gland, nasal mucosa, palatal mucosa
Targets of chorda tyampani/submandibular ganglion?
submandibular and sublingual salivary glands
What do the taste fibers of the facial nerve innervate?
the anterior 2/3 of the tongue. They also synapse in the submandibular ganglion. `
Where are the cell bodies of the sensory fibers of the facial nerve located?
The geniculate ganglion
What do somatic sensory fibers of the facial nerve innervate?
The external ear
Once in the facial canal, where do the somatic motor and somatic sensory fibers of the facial nerve exit the temporal bone?
The stylomastoid foramen
How does the glossopharyngeal nerve leave the cranial cavity?
The jugular foramen
What fiber types does the glossopharyngeal nerve contain?
Somatic motor, preganglionic parasympathetic, somatic sensory, visceral sensory, and taste fibers
Where are the cell bodies of the somatic motor component of the glossopharyngeal nerve?
Nucleus ambiuous
What are the targets of the somatic motor component of the glossopharyngeal nerve?
Stylopharyngeus muscule
Where do preganglionic parasympathetic fibers of the glossopharyngeal nerve originate?
The inferior salivary nucleus
How do the preganglionic parasympathetic fibers of the glossopharyngeal nerve get to their target postganglionic nerve? What ganglion do they synapse in?
The lesser petrosal nerve carries them to the otic ganglion
What are the targets of the postganglionic fibers of the glossopharyngeal nerve
The parotid gland, they stimulate secretion
What do somatic sensory fibers of the glossopharyngeal nerve carry?
Information about pain, temperature and touch from the posterior 1/3 of the tongue, tonsils, soft palate and sides of the pharynx.
Where are the somatic sensory cell bodies, taste fibers, and visceral sensory cell bodies of the glossopharyngeal nerve located?
The inferior ganglion of IX
What are the targets of the visceral sensory fibers of the glossopharyngeal nerve?
Carotid sinus (baroreceptor) and carotid body (chemoreceptor)
How does the vagus nerve exit the cranial cavity?
Jugular foramen
Describe the path of the vagus nerve in the neck?
It passes through the neck in the carotid sheath with the internal jugular vein and common carotid artery.
What branches does the vagus nerve give off in the neck?
The pharyngeal branch, superior laryngeal nerve, right recurrent laryngeal nerve
What fiber types does the vagus nerve contain?
Preganglionic parasympathetic, somatic motor, somatic sensory, visceral sensory and taste fibers
Where do the preganglionic parasympathetic fibers of vagus have their cell bodies located? Where do they synapse?
In the dorsal motor nucleus of vagus. They synapse in intramural ganglia in the wall of the organ.
Where do somatic motor fibers of vagus nerve have their cell bodies located?
nucleus ambiguous
Where do somatic sensory fibers of vagus have their cell bodies located?
Superior (jugular) ganglion of X
What are the targets of the somatic sensory fibers of vagus?
External ear, external tympanic membrane
Where do taste fibers of vagus have their cell bodies located?
inferior ganglion of X
Where do visceral sensory fibers of vagus have their cell bodies located?
inferior (nodose) ganglion of x.
What are the targets of taste fibers from the vagus nerve?
Epiglottis
